In digital transmission systems, error correction plays an important role as a countermeasure for variations in time, frequency, and deterioration of the reception environment. Furthermore, error corrections are applied as countermeasures for multipath interference, interference waves, etc.
In multi-carrier transmissions, such as orthogonal frequency division multiplexing (OFDM), time/frequency transforms of fast Fourier transforms (FFTs) are carried out on a series of data to provide a guard interval, and then transmission is carried out. The series of data that includes the guard interval and the data portion is referred to herein as a frame.
Incidentally, when interference with a high dependency on frequency is present, such as interference for digital television broadcasting signals, e.g., analog television broadcasting signals, it has been found that it is effective to correct it by detecting the frequency carriers of the interference in the frequency domain, and removing the detected interference frequency carriers (this is known as erasure correction).
For example, in order to increase the reliability of the detection methods of interference, detection of the frequency carriers of the interference is performed, by carrying out an integration process or the like, and accumulating the interference components across several frames, and determining whether the interference has exceeded a preset level.
Unfortunately, in situations where the reception state fluctuates by large amounts in time as a result of impulse noise, for example, in the above mentioned integration process, it is difficult to adapt to the large instantaneous changes in the reception level (e.g., to detect the change and to implement proper corrections).